Edit 2: I edited the post a first time to take account of doubts commenting the name 'Sue de Coq'.Further unfriendly comments advising me to rather write the chain as a loop (that was already posted by Clement), are the last straw that breaks the camel's back. So this was my last contribution to this forum. Goodbye, enjoy solving sudoku puzzles !

Last edited by Cenoman on Mon Nov 26, 2018 10:17 pm, edited 2 times in total.

Hi Cenoman! Very nice as usual! Sorry for being nitpicky (again), but are you sure that can be called Sue de Coq, though? I can see a doubly-linked ALS XZ with those nodes:

(2=8'6)r3c13 - (6=45'2)r9c361 - Loop => (same eliminations)

...which is surely a defining characteristic of SDC, but is it enough? The shape is far from a typical SDC (core AA(*)LS in one mini-line + one ALS in the same box + one ALS on the same line as the core). I don't know any extension that would allow such parallel nodes (a, b) in two boxes.

There's a more traditional Sue de Coq with the same eliminations, however:

(Personally I think the loop is the simplest way to express and understand it anyway. I've always hated special SDC and ALS notations because they reveal nothing about the logic to someone who doesn't know the pattern and its notational conventions. For example, I didn't bother to learn about SDCs at all until someone here pointed out that they're just doubly-linked ALS XZs -- which I'd realized were simply loops some time before that. After those revelations both patterns and their eliminations became very easy to understand, unlike the complex monsters they seemed before.)

Hm, i would not call Cenoman's nice 2-digit chain a Sue de Coq, which for me is restricted to one box, one line.Was the definition expanded in the meantime ?

I saw the one with your cells as (8=26)r3c13 -> contradiction r1278c2 (3 digits, 4 cells)You can write it as (8=2)r3c1 - (2=6)r1278c2 - (6=8)r3c3 (only eliminating the 8's)[Added:] Ok, making it a loop and adding the other digits you get the 5,6 eliminations too.

eleven wrote:Hm, i would not call Cenoman's nice 2-digit chain a Sue de Coq, which for me is restricted to one box, one line.

As I said, me too. Its original name was Two-Sector Disjoint Subset, and I think that definition still holds.

Was the definition expanded in the meantime ?

I don't think it's been expanded that way. As far as I know, the original had a 2-3 cell AALS core in a mini-line + two bivalue cells (one in the box and one on the line) containing different core digits. The only extensions I know are extra digits and cells, but still within the one box + one line limit. Larger DDSs with more sectors are possible but I don't think they're called Sue de Coqs.

I saw the one with your cells as (8=26)r3c13 -> contradiction r1278c2 (3 digits, 4 cells)

Me too, but it was easy to turn into a loop which does get all of Cenoman's eliminations.

You can write it as (8=2)r3c1 - (2=6)r1278c2 - (6=8)r3c3 (only eliminating the 8's)[Added:] Ok, making it a loop and adding the other digits you get the 5,6 eliminations too.

Exactly. That's why I'd write those bystander digits here (and in any ALS loop), because they get locked and cause those extra eliminations. Your loop (which is basically the same I presented in my previous post, just written differently) is an actual Sue de Coq, too.

Cenoman wrote:Edit 2: I edited the post a first time to take account of doubts commenting the name 'Sue de Coq'.

Sorry, I apparently missed that edit the first time.

Further unfriendly comments advising me to rather write the chain as a loop (that was already posted by Clement), are the last straw that breaks the camel's back. So this was my last contribution to this forum. Goodbye, enjoy solving sudoku puzzles !

That's a real shame. I'm truly sorry if something in my comments offended you. That was not my intention the least bit. I have zero reason to be anything but friendly to you as you've helped me learn so much. I can understand if someone doesn't appreciate my habit of questioning various things, but I can assure you that there's nothing unfriendly about it. It's just part of my own learning process. I didn't see anything unfriendly in eleven's comments either.

I think you're overreacting, and I sincerely hope that you change your mind and come back. Your contributions will be missed otherwise. It would have been enough to tell me/us that you don't want your solutions to be commented. I could respect that, although it's not something I can really understand natively. Personally I gladly welcome any criticism because it helps me (and possibly others) to learn, and it's the same reason why I also give it rather freely. Learning, and helping others to do the same, are my only goals here.